The price of an e-commerce platform will depend on what features you wish to incorporate. Both Shopify and Bigcommerce are affordable, and even a startup business can find extensions that are not too expensive.
Every business has its own needs; it is, therefore, important that whichever e-commerce platform you opt for, gives you the flexibility to customize it as per your requirements. Both Shopify and Bigcommerce give you the option to integrate whatever extensions you need for your business. Whether it is inventory management, customer management platform, promotions, among others; you will get them in their marketplace.
Once you have everything you need, you can efficiently run your online store from the dashboard. The best part about customizing your e-commerce platform is that you only include what you need, and have first-hand knowledge of everything you have done.